HereandNow

Christchurch quake may portend major seismic activity for Japan

On Feb 22, New Zealand's second-largest metropolitan area, Christchurch, was struck by its second major earthquake in five months. The magnitude 6.3 temblor occurred at 12:50 p.m. local time, when many people were outside their homes.

The Christchurch quake released less than 5% of the total energy compared to the magnitude 7.3 Hanshin-Awaji quake that devastated the city of Kobe in January 1995. Yet the structural damage was horrific; as many as one-third the buildings in the city's central area may have to be demolished.

"Even for an M-6 quake occurring at a relatively shallow level of 5 kilometers beneath the Earth's surface, the scale of the damage was unexpected," Yasumichi Mifune, an authority on urban disasters, tells Weekly Playboy (March 14). "Looking carefully at videos and photos, the damage was not only confined to older edifices built of brick, such as the cathedral, but many new structures as well.

"It is certain that New Zealand, which like Japan is located in a region of frequent seismic activity, has been adopting earthquake-resistant architecture, but the disaster may have been primed by subterranean factors," says Mifune.

What Mifune means, the magazine explains, was that a previous magnitude 7.0 quake that occurred last Sept 4, with an epicenter 40 kilometers west of the city, may have caused building structures in Christchurch to weaken. Although visible damage was from the September quake was minimal, the Feb 22 "aftershock" may have served as a straw that broke the camel's back.

As professor emeritus Masaaki Kimura of Ryukyu University points out to the magazine, activity along tectonic plates tend to follow a cycle of about 30 years. The huge volcanic eruption of Mt St Helens in Washington State in 1980, for example, was followed by the magnitude 6.7 eruption along California's San Andreas fault. Likewise the 1991 eruption of Mt Pinatubo in the Philippines was followed in 2000 by seismic activity along the Marianas Trench. In 1994, movement along the Australia-Eurasia plate culminated in the catastrophic magnitude 9.3 quake off Sumatra in December 2004 and tsunami that resulted in the loss of over 200,000 lives.

What does this 30-year pattern of volcanic activity followed by a major seismic movement portend for Japan?

"Considering how the entire Pacific region maintains its balance by alternating the earthquakes and volcanic eruptions between west and east, it would suggest a strong possibility that, considering the frequency of activity off the coast of South America these past several years, Japan will be affected," Kimura remarks.

Although it's located nearly 10,000 kilometers north of New Zealand, the recent eruption of the Shinmoedake volcano in Miyazaki Prefecture may be related to activity by same Pacific Plate.

"While the Japan sector of the Pacific rim has been comparatively quiet, we should at last start anticipating the shift to more concentrated movements in the earth's crust," Kimura says.

Other signs of nearby activity on mainland Asia, such precursors of an eruption of Mt. Baekdu, on the border of North Korea and China, suggest the possibility of a shift along a major fault running through Kyushu and Honshu as far as the Chubu area, as well as increases of medium-sized quakes of magnitude 4 to 5 class in east Japan. Even a quake smaller than magnitude 7, if occurring at the relatively shallow depth of 10 to 30 kilometers beneath the surface in the greater Kanto region, could cause incalculable damage to the lives of the 30 million people living there.

Ominously, the New Zealand quakes portend increased danger for areas along the northwest section of the Pacific Plate.

Mar. 9, 2011
01:15 pm JST

Tokyo had a nice little rumble this morning that had our building shaking for a good five minutes. It was a "shindo 5" in NorthEast Japan that did it. Then we had two more aftershocks that kept the building swaying for a good 10-15 minutes in total.

Mar. 3, 2011
03:08 pm JST

I have no way of telling whether the experts quoted here are right or wrong, but is Playboy Weekly the best Japan Today could find? Isn't there a more respectable and reliable source of information than the usual scaremongers?

Japan has been and will be affected by powerful earthquakes, so you should take precautions anyway if you haven't quake-proofed your home already, whatever the recent one in NZ portends.

Mar. 2, 2011
08:05 pm JST

I would welcome a JT question on what readers are putting into their emergency kitbox/bag in the front hall.

I think there will be many "Big Ones" in the years to come, not only in Japan.

By my bed I always keep a bottle of water and a torch/flashlight with a whistle tied to it. Interestingly, many people in a hospital in Kobe survived their Big One owing to the fact that their bedsteads stopped the concrete ceiling from crushing them flat. Now, do you prefer futon or a bed frame, hehehe?

Mar. 2, 2011
12:31 pm JST

Japnlan, the Arkansas and Missouri quakes are probably due to fracking.

The science of predicting earthquakes has not progressed all that much from burning turtle bones and analyzing their cracks - well, the "when" part hasn't, at least. Much progress has been made in identifying faults and understanding their histories and likely future movement, but when dealing with a geological scale, a hundred years is a mere blink. To say that the New Zealand quake portends imminent seismological activity in Japan is speaking without knowing.

Mar. 1, 2011
12:13 pm JST

Except Japan's anti-quake architecture technologies and required building codes being used for years, Most of other countries in Pacific Asia zones have less seriousness toward such important procedures in building houses and constructions.

It is not a case of less seriousness, it is a case of lack of awareness. Japanese people have been in Japan for many, many centuries, and have frequent earthquakes. They didn't need the relatively new science of plate techtonics to tell them they have earthquakes. New Zealand and also Canada and the US northwest are in areas of infrequent but potentially powerful earthquakes, and the cities were built long before the dangers were understood. Very different situation from Japan, and as we saw in Christchurch a very serious problem.

Mar. 1, 2011
07:13 am JST

Feb. 28, 2011
08:34 pm JST

Have a good presence of mind when the "big one" strikes, follow your drills, keeep emergency kits loaded near your entrance/exit.
Does'nt cost a ton, but might be enough to save your life.
Been living in japan for a long time and somehow believe it has been relatively calm over the last 3-4 years without any major quake to hit Tokyo.

Feb. 28, 2011
08:09 pm JST

Except Japan's anti-quake architecture technologies and required building codes being used for years, Most of other countries in Pacific Asia zones have less seriousness toward such important procedures in building houses and constructions. To use Japan's construction codes can increase a cost of building houses and hight-rises. Even in New Zealand, aftermath consequences can still cause danger to existing building and houses because we need to check foundations and other unseen damages of each house and building before residents in this city can make sure they are living in a stable structure. Weekly Playboy magazine is some special men magazines in Japan like Playboy in America.

Feb. 28, 2011
05:23 pm JST

Feb. 28, 2011
04:23 pm JST

If you haven't done so already, earthquake proof your home, especially large and heavy pieces of furniture, anything that might topple over, and everything made of glass (including windows) and pottery. This will reduce your likelihood of getting crushed and cut. When the big one hits, anything not secured in your home may become a lethal projectile. My own biggest concern right now: How to secure my large fishtank sitting on a deep window ledge, and my tall B&W speakers.